Methods of forming and repairing cutting element pockets in earth-boring tools with depth-of-cut control features, and tools and structures formed by such methods

ABSTRACT

Methods of forming and repairing earth-boring tools include providing wear-resistant material over a temporary displacement member to form a cutting element pocket in a body and a depth-of-cut control feature using the wear-resistant material. In some embodiments, the wear-resistant material may comprise a particle-matrix composite material. For example, a hardfacing material may be built up over a temporary displacement member to form or repair a cutting element pocket and provide a depth-of-cut control feature. Earth-boring tools include a depth-of-cut control feature comprising a wear-resistant material. The depth-of-cut control feature is configured to limit a depth-of-cut of a cutting element secured within a cutting element pocket partially defined by at least one surface of the depth-of-cut control feature. Intermediate structures formed during fabrication of earth-boring tools include a depth-of-cut control feature extending over a temporary displacement member.

TECHNICAL FIELD

The present invention relates to methods of forming earth-boring toolshaving cutting elements disposed in cutting element pockets, and toearth-boring tools and structures formed by such methods.

BACKGROUND

Wellbores are formed in subterranean formations for various purposesincluding, for example, extraction of oil and gas from subterraneanformations and extraction of geothermal heat from subterraneanformations. Wellbores may be formed in subterranean formations usingearth-boring tools such as, for example, drill bits (e.g., rotary drillbits, percussion bits, coring bits, etc.) for drilling wellbores andreamers for enlarging the diameters of previously-drilled wellbores.Different types of drill bits are known in the art including, forexample, fixed-cutter bits (which are often referred to in the art as“drag” bits), rolling-cutter bits (which are often referred to in theart as “rock” bits), diamond-impregnated bits, and hybrid bits (whichmay include, for example, both fixed cutters and rolling cutters).

To drill a wellbore with a drill bit, the drill bit is rotated andadvanced into the subterranean formation. As the drill bit rotates, thecutters or abrasive structures thereof cut, crush, shear, and/or abradeaway the formation material to form the wellbore. A diameter of thewellbore drilled by the drill bit may be defined by the cuttingstructures disposed at the largest outer diameter of the drill bit.

The drill bit is coupled, either directly or indirectly, to an end ofwhat is referred to in the art as a “drill string,” which comprises aseries of elongated tubular segments connected end-to-end that extendsinto the wellbore from the surface of the formation. Often various toolsand components, including the drill bit, may be coupled together at thedistal end of the drill string at the bottom of the wellbore beingdrilled. This assembly of tools and components is referred to in the artas a “bottom hole assembly” (BHA).

The drill bit may be rotated within the wellbore by rotating the drillstring from the surface of the formation, or the drill bit may berotated by coupling the drill bit to a down-hole motor, which is alsocoupled to the drill string and disposed proximate the bottom of thewellbore. The down-hole motor may comprise, for example, a hydraulicMoineau-type motor having a shaft, to which the drill bit is mounted,that may be caused to rotate by pumping fluid (e.g., drilling mud orfluid) from the surface of the formation down through the center of thedrill string, through the hydraulic motor, out from nozzles in the drillbit, and back up to the surface of the formation through the annularspace between the outer surface of the drill string and the exposedsurface of the formation within the wellbore.

It is known in the art to use what are referred to in the art as a“reamers” (also referred to in the art as “hole opening devices” or“hole openers”) in conjunction with a drill bit as part of a bottom holeassembly when drilling a wellbore in a subterranean formation. In such aconfiguration, the drill bit operates as a “pilot” bit to form a pilotbore in the subterranean formation. As the drill bit and bottom holeassembly advances into the formation, the reamer device follows thedrill bit through the pilot bore and enlarges the diameter of, or“reams,” the pilot bore.

As a wellbore is being drilled in a formation, axial force or “weight”is applied to the drill bit (and reamer device, if used) to cause thedrill bit to advance into the formation as the drill bit drills thewellbore therein. This force or weight is referred to in the art as the“weight-on-bit” (WOB).

It is known in the art to employ what are referred to as “depth-of-cutcontrol” (DOCC) features on earth-boring drill bits. For example, U.S.Pat. No. 6,298,930 to Sinor et al., issued Oct. 9, 2001 discloses rotarydrag bits that including exterior features to control the depth-of-cutby cutters mounted thereon, so as to control the volume of formationmaterial cut per bit rotation as well as the torque experienced by thebit and an associated bottom-hole assembly. The exterior features mayprovide sufficient bearing area so as to support the drill bit againstthe bottom of the borehole under weight-on-bit without exceeding thecompressive strength of the formation rock.

BRIEF SUMMARY

In some embodiments, the present invention includes methods of formingearth-boring tools. A cutting element pocket is partially formed in asurface of a body of an earth-boring tool, and a temporary displacementmember is inserted into the partially formed cutting element pocket. Aparticle-matrix composite material is provided over an area of thesurface of the body of the earth-boring tool adjacent the partiallyformed cutting element pocket, and over a portion of a surface of thetemporary displacement member. Formation of the cutting element pocketis completed and a depth-of-cut control feature is formed using theparticle-matrix composite material.

In additional embodiments, the present invention includes methods ofrepairing earth-boring tools. A cutting element is removed from acutting element pocket in a body of an earth-boring tool, and atemporary displacement member is inserted into the cutting elementpocket in the body of the earth-boring tool. A depth-of-cut controlfeature comprising a particle-matrix composite material is provided overa portion of a surface of the temporary displacement member and bondedto the body of the earth-boring tool proximate the temporarydisplacement member. The depth-of-cut control feature is formed to havea size and shape configured to limit a depth-of-cut of a cutting elementto be secured within a cutting element pocket defined by at least onesurface of the depth-of-cut control feature and at least one surface ofthe body of the earth-boring tool.

Additional embodiments of the present invention include methods ofrepairing earth-boring tools in which hardfacing material is depositedover an area of a surface of a body of an earth-boring tool adjacent acutting element pocket and over a portion of a surface of a temporarydisplacement member within the pocket. The hardfacing material isdeposited over the temporary displacement member in a volume sufficientto repair the cutting element pocket and form a depth-of-cut controlfeature from the hardfacing material.

In additional embodiments, the present invention includes earth-boringtools that include a body and a depth-of-cut control feature on asurface of the body. The depth-of-cut control feature comprises aparticle-matrix composite material and is configured to limit adepth-of-cut of at least one cutting element secured to the body withina cutting element pocket. The cutting element pocket is partiallydefined by at least one surface of the body and at least one surface ofthe depth-of-cut control feature.

Yet further embodiments of the present invention include intermediatestructures formed during fabrication of an earth-boring tool. Theintermediate structures include a body of an earth-boring tool having atleast one surface partially defining a cutting element pocket in thebody, a temporary displacement member disposed within the cuttingelement pocket, and a depth-of-cut control feature on a surface of thebody that extends partially over the temporary displacement member.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

While the specification concludes with claims particularly pointing outand distinctly claiming that which is regarded as the present invention,the advantages of embodiments of this invention may be more readilyascertained from the following description of certain embodiments of theinvention when read in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a perspective view of an embodiment of an earth-boring tool ofthe present invention;

FIG. 2 is an enlarged view of a portion of the earth-boring tool of FIG.1 illustrating a cutting element disposed in a cutting element pocket atleast partially defined by a depth-of-cut control feature;

FIG. 3 is a cross-sectional view of the cutting element and thedepth-of-cut control feature shown in FIG. 2;

FIG. 4 is a cross-sectional view of a body of an earth-boring toolillustrating a partially-formed cutting element pocket in the body;

FIG. 5 is a cross-sectional view like that of FIG. 4 illustrating atemporary displacement member disposed within the partially-formedcutting element pocket in the body of the earth-boring tool; and

FIG. 6 is a cross-sectional view like that of FIG. 5 illustrating adepth-of-cut control feature disposed over the temporary displacementmember and a portion of the body adjacent the temporary displacementmember.

DETAILED DESCRIPTION

Illustrations presented herein are not meant to be actual views of anyparticular device or system, but are merely idealized representationsthat are employed to describe embodiments of the present invention.Additionally, elements common between figures may retain the samenumerical designation.

An embodiment of a drill bit 10 of the present invention is shown inFIG. 1. The drill bit 10 shown in FIG. 1 is a fixed-cutter rotary drillbit that includes a plurality of cutting elements 12 secured to a bitbody 14 within cutting element pockets 16. The bit body 14 includes aplurality of blades 18 that define fluid courses 20 therebetween. Aplurality of cutting elements 12 are secured to each of the blades 18.The drill bit 10 further includes a connection portion 28 that isconfigured for attaching the drill bit 10 to a drill string (not shown)or a down-hole motor (not shown). For example, the connection portion 28may comprise a threaded pin on a shank attached to the bit body 14 ofthe drill bit 10. Such a threaded pin may conform to industry standardssuch as those promulgated by the American Petroleum Institute (API).

The drill string, a down-hole motor (e.g., a hydraulic Moineau-typemotor), or both the drill string and the down-hole motor may be used torotate the drill bit 10 within a wellbore to cause the cutting elements12 to cut (e.g., shear) away the exposed material of a subterraneanformation within the wellbore.

The bit body 14 may be formed from and comprise various materialsincluding, for example, metal alloys (e.g., steel) and particle-matrixcomposite materials. Such particle-matrix composite materials include,for example, cermet materials comprising hard ceramic particles (e.g.,tungsten carbide, titanium carbide, tantalum carbide, boron nitride,silicon carbide, silicon nitride, etc.) embedded within a metal alloymatrix material (e.g., a copper-based alloy, an iron-based alloy, acobalt-based alloy, a nickel-based alloy, etc.). Bit bodies 14comprising particle-matrix composite materials can be formed using, forexample, infiltration processes as well as pressing and sinteringprocesses, as known in the art.

Each of the blades 18 of the drill bit 10 extends around the face of thebit body 14 from one of a central cone region and a nose region on theface of the bit body 14 to the lateral sides of the bit body 14. Blades18 that extend from the central cone region of the bit body 14 arereferred to as “primary” blades, while the blades 18 that extend fromthe nose region (but not the central cone region) are referred to as“secondary” blades. Each of the blades extends longitudinally along atleast a portion of the lateral sides of the bit body 14. The radialouter-most surfaces of the blades on the lateral sides of the bit body14 are referred to as gage surfaces 22 of the drill bit 10, and definethe largest diameter of the drill bit 10 and, hence, the diameter of thewellbore formed by drilling with the drill bit 10. The sections of theblades 18 that extend longitudinally along the lateral sides of the bitbody 14 are referred to as the gage portions of the blades 18. The fluidcourses 20 defined between the gage portions of the blades 18 are oftenreferred to in the art as “junk slots.”

The cutting elements 12 of the drill bit 10 shown in FIG. 1 comprisepolycrystalline diamond compact (PDC) cutting elements, and have arelatively thin layer of polycrystalline diamond material formed on, orattached to, a generally planar end surface of a cylindrical,cobalt-cemented tungsten carbide cutter body. The layer ofpolycrystalline diamond material on the substrate body is often referredto in the art as a diamond “table.” In additional embodiments, thecutting elements 12 may comprise any other type of fixed-cutter cuttingelement known in the art, such as, for example, cutting elements atleast substantially comprised of cemented tungsten carbide that do nothave any diamond table thereon.

In some embodiments, the drill bit 10 also may include a plurality ofback-up cutting elements 12′. Each back-up cutting element 12′ maycorrespond to, and back up, a primary cutting element 12. In otherwords, each back-up cutting element 12′ may be disposed rotationallybehind a primary cutting element 12, but at the same longitudinal andradial position on the drill bit 10, such that the back-up cuttingelement 12′ will follow the primary cutting element 12 to which itcorresponds through the same cutting path as the drill bit 10 is used todrill a wellbore. Each back-up cutting element 12′ may be mounted to ablade 18 within a cutting element pocket 16 such that the back-upcutting element 12′ is partially recessed relative to the surroundingsurface of the blade 18.

A relatively large fluid plenum (e.g., a bore) (not shown) extendspartially through the bit body 14 of the drill bit 10, and a pluralityof fluid passageways (not shown) extend from the fluid plenum to theface of the drill bit 10. Nozzles (not shown) may be fixed to the bitbody 14 within these fluid passageways proximate the face of the bitbody 14.

As a wellbore is drilled with the drill bit 10, drilling fluid is pumpedfrom the surface of the formation being drilled down through the drillstring, through the fluid plenum and the fluid passageways within thebit body 14, and out through the nozzles into the fluid courses 20between the blades 18 on the exterior of the drill bit 10. The fluidflows around the face of the drill bit 10 through the fluid courses 20,sweeping away formation cuttings and detritus in the process, and intothe annular space around the exterior surfaces of the drill string. Thefluid flows up through this annular space around the exterior surfacesof the drill string to the surface of the formation, carrying with itthe formation cuttings and detritus created by the drilling action ofthe drill bit 10.

In accordance with embodiments of the present invention, one or more ofthe cutting element pockets 16 is defined by at least one surface of adepth-of-cut control feature 50 on the face of the drill bit 10. In theembodiment shown in FIG. 1, the drill bit 10 includes one depth-of-cutcontrol feature 50 on a surface of each blade 18 of the bit body 14. Thedepth-of-cut control features 50 comprise a relatively wear-resistantmaterial such as, for example, a particle-matrix composite materialcomprising hard particles (e.g., tungsten carbide, titanium carbide,tantalum carbide, boron nitride, silicon carbide, silicon nitride, etc.)embedded within a metal alloy matrix material (e.g., a copper-basedalloy, an iron-based alloy, a cobalt-based alloy, a nickel-based alloy,etc.). In some embodiments, the depth-of-cut control features 50 maycomprise what is referred to in the art as a “hardfacing” material,which is a particle-matrix composite material that may be applied tosurfaces of a body using welding techniques (e.g., oxy-acetylene welding(OAW) processes, metal-inert gas (MIG) welding processes, tungsten-inertgas (TIG), plasma arc welding (PAW) processes (including(plasma-transferred arc welding (PTAW) processes), and flame-sprayprocesses.

In the embodiment shown in FIG. 1, one depth-of-cut control feature 50is provided on each of the blades 18. Each depth-of-cut control feature50 partially surrounds a cutting element 12 on a nose region on the faceof the drill bit 10, and is configured (e.g., sized and shaped) so as tolimit a depth-of-cut of the corresponding cutting element 12 that ispartially surrounded by the depth-of-cut control feature 50. By limitingthe depth-of-cut of the cutting elements 12 that are partiallysurrounded by the depth-of-cut control features 50, the depth-of-cutcontrol features 50 may effectively (e.g., indirectly) limit thedepth-of-cut of other cutting elements 12 of the drill bit 10.

In additional embodiments of the invention, the drill bit 10 may includemore or less of the depth-of-cut control features 50. For example, eachof the cutting elements 12 of the drill bit 10 may be partiallysurrounded by a depth-of-cut control feature 50. In other embodiments,cutting elements 12 in other regions of the drill bit (i.e., in one ormore of the central cone region, the shoulder region, and the gageregion) may be partially surrounded by depth-of-cut control features 50.

FIG. 2 is an enlarged view of a portion of the drill bit 10 of FIG. 1illustrating a depth-of-cut control feature 50 that at least partiallysurrounds a cutting element 12 on one of the blades 18 of the drill bit10. As shown in FIG. 2, the depth-of-cut control feature 50 is disposedon, and bonded to, an area on a surface 19 of the blade 18 that isrotationally behind the cutting element 12, as well as areas on thelateral sides of the cutting element 12. Thus, forces acting on thedepth-of-cut control feature 50 by a surface of a formation rubbingagainst the depth-of-cut control feature 50 are transferred to the blade18 of the drill bit 10. The depth-of-cut control feature 50 also extendsover a portion of the cutting element 12. In particular, thedepth-of-cut control feature 50 extends over a substantial portion(e.g., greater than about 50%) of an area of a cylindrical side surface40 of the cutter body of the cutting element 12 that is exposed outsideof the blade 18. In other words, of the area of a cylindrical sidesurface 40 of the cutter body not bonded to the blade 18, a substantialportion (e.g., greater than about 50%) of this area may be bonded to thedepth-of-cut control feature 50. The depth-of-cut control feature 50also may be bonded to an area of a substantially planar back (i.e.,rotationally trailing) surface 42 (FIG. 3) of the cutter body of thecutting element 12.

FIG. 3 is a cross-sectional view of the cutting element 12 and thedepth-of-cut control feature 50 shown in FIG. 2. As shown in FIG. 3, thecutting element pocket 16 is partially defined by an arcuate surface 52of the depth-of-cut control feature 50, and partially defined by anarcuate surface 54 of the blade 18 of the bit body 14. The arcuatesurface 52 of the depth-of-cut control feature 50 and the arcuatesurface 54 of the blade 18 of the bit body 14 may be coextensive withone another to define an at least substantially cylindrical surface ofthe cutting element pocket 16 that is sized and configured to bedisposed adjacent the at least substantially cylindrical lateral sidesurface 40 of the cutter body of the cutting element 12. The cuttingelement pocket 16 is further partially defined by a back surface, whichmay be at least substantially planar in some embodiments. For example,the substantially planar back surface may comprise a planar surface 56of the blade 18 of the bit body 14, a planar surface 58 of thedepth-of-cut control feature 50, or both a planar surface 56 of theblade 18 of the bit body 14 and a planar surface 58 of the depth-of-cutcontrol feature 50, the planar surface 56 and the planar surface 58being coextensive and continuous with one another, as shown in FIG. 3.

The cutting element 12 may be secured to the blade 18 of the bit body 14and the depth-of-cut control feature 50 within the cutting elementpocket 16 using a bonding material 60. The bonding material 60 maycomprise a metal alloy having a relatively low melting point (e.g.,below about 1,300° F. (e.g., a silver-based brazing alloy). Asubstantially uniform, minimal gap (e.g., between about one thousandth(0.001) of an inch and about eight thousands (0.008) of an inch) may beprovided between the cutting element 12 and the surfaces defining thecutting element pocket 16 to provide clearance for the bonding material60. The gap between the cutting element 12 and the surfaces defining thecutting element pocket 16 may be selected to increase (e.g., maximize)capillary forces that are used to draw the bonding material 60, in aliquid state, into the gap between the cutting element 12 and thesurfaces defining the cutting element pocket 16 after positioning thecutting element 12 within the cutting element pocket 16.

As shown in FIG. 3, the depth-of-cut control feature 50 extends apredetermined distance D₁ above the surface 19 of the blade 18 of thebit body 14 adjacent the cutting element pocket 16. Thus, thedepth-of-cut of the cutting element 12 is limited to a depth D₂ definedas the difference between distance D₃ by which the cutting element 12protrudes from the surface 19 of the blade 18 of the bit body 14adjacent the cutting element pocket 16, and the predetermined distanceD₁ by which the depth-of-cut control feature 50 extends above thesurface 19 of the blade 18 of the bit body 14 adjacent the cuttingelement pocket 16.

In some embodiments of the present invention, each depth-of-cut controlfeature 50 may comprise a predetermined minimum surface area at thepredetermined distance D₁ above the surface of the blade 18 of the bitbody 14 adjacent the cutting element pocket 16. Furthermore, the sum ofthese areas of these depth-of-cut control features 50 may provide atotal “rubbing area” on the depth-of-cut control features 50 that isconfigured to distribute the forces applied to the formation by thedrill bit 10, due to the weight-on-bit, over a sufficiently large areasuch that the stresses applied to the areas of the formation in contactwith the depth-of-cut control features 50 by the drill bit 10 will notexceed the confined compressive strength of the formation, which couldresult in crushing of the areas of the formation that are in contactwith and rubbing against the depth-of-cut control features 50. Suchcrushing of the formation by the depth-of-cut control features 50 may bean undesirable phenomenon during the drilling process, resulting in anexcessive depth-of-cut, the potential for bit balling and excessivetorque such that, if a down-hole motor is used, stalling may occur.

As previously discussed, in some embodiments, the drill bit 10 mayinclude a plurality of back-up cutting elements 12′ that are configuredand positioned to back up a plurality of primary cutting elements 12.FIG. 3 illustrates a single primary cutting element 12 and a singleback-up cutting element 12′ that is configured and positioned to back upthe primary cutting element 12. The primary cutting element 12 may bedisposed in a cutting element pocket 16 that is at least partiallydefined by a depth-of-cut control feature 50, as previously discussedherein. In some embodiments of the present invention, the exposure ofthe back-up cutting element 12′ may be selected in relation to thepredetermined distance D₁ by which the depth-of-cut control feature 50extends above the surface 19 of the blade 18 of the bit body 14 adjacentthe cutting element pocket 16. In other words, the distance by which theback-up cutting element 12′ extends above the surface 19 of the blade 18of the bit body 14 may be selected in relation to the predetermineddistance D₁ by which the depth-of-cut control feature 50 extends abovethe surface 19 of the blade 18 of the bit body 14. For example, in someembodiments, the exposure of the back-up cutting element 12′ may besubstantially equal to the predetermined distance D₁ by which thedepth-of-cut control feature 50 extends above the surface 19 of theblade 18 of the bit body 14.

As another example, the exposure of the back-up cutting element 12′initially (upon manufacture of the drill bit 10) may be less than thepredetermined distance D₁ by which the depth-of-cut control feature 50extends above the surface 19 of the blade 18 of the bit body 14. Thus,as the drill bit 10 is used to drill a wellbore, the depth-of-cutcontrol feature 50 will initially prevent the back-up cutting element12′ from engaging and cutting the formation material. However, as thedepth-of-cut control feature 50 wears away, the back-up cutting element12′ will eventually engage with and begin to cut the formation material.In some embodiments, the depth-of-cut control feature 50 may have ashape that causes the area of the depth-of-cut control feature 50 incontact with the formation to increase as the depth-of-cut controlfeature 50 wears away. Thus, at the time the back-up cutting element 12′engages the formation, the area of the depth-of-cut control feature 50in contact with the formation may be larger than an area of thedepth-of-cut control feature 50 in contact with the formation uponinitial commencement of the drilling process.

As a result, the exposure of the back-up cutting elements 12′ and theshape of the depth-of-cut control features 50 may be selected andconfigured such that, at the time the depth-of-cut control features 50have worn to an extent that results in initial engagement of the back-upcutting elements 12′ with the formation, the area of the depth-of-cutcontrol features 50 in contact with and rubbing against the formationwill be at least equal to a predetermined minimum surface area. Aspreviously discussed, this minimum surface area may be large enough thatthe stresses applied to the areas of the formation in contact with thedepth-of-cut control features 50 by the drill bit 10 will not exceed theconfined compressive strength of the formation.

In some embodiments of the present invention, the depth-of-cut controlfeatures 50 may be formed from and at least substantially comprised of ahardfacing material of at least substantially similar materialcomposition. In additional embodiments, at least one depth-of-cutcontrol feature 50 may be formed from a hardfacing material having amaterial composition that differs from the material composition ofanother, different hardfacing material used to form another depth-of-cutcontrol feature 50 on the drill bit 10. For example, one hardfacingmaterial used to form a depth-of-cut control feature 50 may exhibit arelatively higher wear resistance relative to different hardfacingmaterial used to form another different depth-of-cut control feature 50of the drill bit 10.

An embodiment of a method of the present invention that may be used toform an earth-boring tool, such as the drill bit 10 shown in FIGS. 1through 3, is described below with reference to FIGS. 4 through 6.

Referring to FIG. 4, the bit body 14 (FIG. 1) (including the blades 18thereof) may be fabricated using conventional processes known in theart. In some embodiments, however, the outer surfaces 19 of the blades18 proximate one or more of the cutting element pockets 16 (FIG. 1) maybe recessed relative to previously known bit bodies 14 of comparableconfiguration. In other words, a recess 46 may be formed in the surface19 of the blade 18 proximate (e.g., adjacent and rotationally behind)one or more of the cutting element pockets 16 to be formed therein. InFIG. 4, a partially formed cutting element pocket 16′ extends into theblade 18 of the bit body 14. The partially formed cutting element pocket16′ shown in FIG. 4 includes an arcuate surface 54 of the blade 18 ofthe bit body 14 (which may be at least substantially cylindrical anddefine a partial cylinder), as well as an at least substantially planarsurface 56 of the blade 18 of the bit body 14 that intersects thearcuate surface 54 and is oriented generally perpendicular to thearcuate surface 54 along the intersection therebetween.

Referring to FIG. 5, a temporary displacement member 66 may be insertedinto, and secured within, the partially formed cutting element pocket16′ in the blade 18 of the bit body 14 (FIG. 1). A temporarydisplacement member 66 also may be inserted into, and secured within,any cutting element pocket or partially formed cutting element pocket inthe blade 18 that is configured to receive back-up cutting elements 12′therein, as previously described in relation to FIGS. 1 and 3.

The temporary displacement member 66 may comprise, for example, graphiteor a porous ceramic material (e.g., a ceramic oxide of Al, Si, Mg, Y,etc.) that may be subsequently removed from the cutting element pocket16, as described below. By way of example and not limitation, thetemporary displacement member 66 may comprise aluminum oxide (Al₂O₃),silicon oxide (SiO₂), or a combination of aluminum oxide and siliconoxide. As one non-limiting example, the temporary displacement member 66may comprise approximately 95% by weight aluminum oxide, and about 5% byweight silicon oxide. Furthermore, the temporary displacement member 66may have a size and shape at least substantially similar to that of acutting element 12 to be subsequently secured within the cutting elementpocket 16. For example, if the cutting element 12 is at leastsubstantially cylindrical, the temporary displacement member 66 also maybe at least substantially cylindrical and may have a diameter at leastsubstantially equal to that of the cutting element 12 (although thetemporary displacement member 66 may be longer or shorter than thecutting element 12).

The temporary displacement member 66 may be secured within the partiallyformed cutting element pocket 16′ (FIG. 4) using, for example, anadhesive such as, for example, an epoxy material or another adhesivematerial that will not significantly degrade, until desired, uponfurther processing (e.g., an epoxy or adhesive that can be used attemperatures up to about 1,000° F. or more). In additional embodiments,the temporary displacement member 66 may be secured within the partiallyformed cutting element pocket 16′ by providing an interference fit or ashrink fit between the temporary displacement member 66 and thesurrounding surfaces of the blade 18 of the bit body 14.

Referring to FIG. 6, after securing the temporary displacement member 66within the partially formed cutting element pocket 16′ in the blade 18of the bit body 14 (FIG. 1), a depth-of-cut control feature 50 may beformed or otherwise provided over at least a portion of the temporarydisplacement member 66 and a portion of the surface 19 of the blade 18of the bit body 14 adjacent the temporary displacement member 66.Provision of the depth-of-cut control feature 50 over the temporarydisplacement member 66 and the surrounding surface 19 of the blade 18may complete the formation of the cutting element pocket 16 in the drillbit 10.

As previously discussed, in some embodiments, the depth-of-cut controlfeature 50 may comprise a particle-matrix composite material. In suchembodiments, such a particle-matrix composite material may be depositedor otherwise provided over the temporary displacement member 66 and thesurrounding surface 19 of the blade 18 to complete the formation of thecutting element pocket 16 and to form the depth-of-cut control feature50. Furthermore, in embodiments in which the particle-matrix compositematerial comprises a hardfacing material, the hardfacing material may bedeposited over the temporary displacement member 66 and the surroundingsurface 19 of the blade 18 using a welding process. As hardfacingmaterial is deposited over and adjacent the temporary displacementmember 66 and the surrounding surface 19 of the blade 18, the hardfacingmaterial may be built up through sequential depositions or overlays ofbeads or layers of welding material to form the depth-of-cut controlfeature 50 and complete the formation of the cutting element pocket 16using the hardfacing material.

As previously discussed with reference to FIG. 3, the hardfacingmaterial may be built up over the temporary displacement member 66 andthe surrounding surface 19 of the blade 18 until the hardfacing materialprojects from the surface of the blade 18 by a predetermined distance D₁(FIG. 3). Furthermore, as previously discussed with reference to FIG. 3,the hardfacing material may be built up to provide a predeterminedminimum surface area of the hardfacing material at the predetermineddistance D₁ over the surface of the blade 18 of the bit body 14.

In additional embodiments of the present invention, the depth-of-cutcontrol feature 50 may be separately formed from the blade 18 of the bitbody 14 and subsequently attached thereto. As a non-limiting example,the depth-of-cut control feature 50 may comprise a cemented carbidestructure (e.g., a structure formed from and at least substantiallycomprising a cobalt-cemented tungsten carbide material). Such a cementedcarbide structure may be formed by using pressing and sinteringtechniques, such as techniques substantially similar to thoseconventionally used to form cemented tungsten carbide inserts for drillbits and other earth-boring tools. Such a separately formed depth-of-cutcontrol feature 50 may then be attached to the blade 18 of the bit body14 using a bonding material, such as the bonding material 60 previouslydescribed herein and used to secure the cutting element 12 within thecutting element pocket 16.

After forming or otherwise providing the depth-of-cut control feature 50on the drill bit 10, the temporary displacement member 66 may be removedfrom the cutting element pocket 16. In some instances, it may bepossible to simply pull the depth-of-cut control feature 50 out from thecutting element pocket 16 by hand or with the assistance of a tool ortools, such as, for example, pliers. In other instances, the temporarydisplacement member 66 may be fractured (e.g., using a chisel and/or ahammer) within the cutting element pocket 16, and the resulting piecesof the fractured temporary displacement member 66 may be removed fromthe cutting element pocket 16. In other instances, the temporarydisplacement member 66 may be ground or blasted (e.g., sand-blasted) outfrom the cutting element pocket 16. Furthermore, combinations of theabove mentioned techniques may be used to completely remove thetemporary displacement member 66 from the cutting element pocket 16.

After removing the temporary displacement member 66 from the cuttingelement pocket 16, a cutting element 12 may be inserted into the cuttingelement pocket 16 and secured therein using a bonding material 60 usingconventional processes known in the art. If employed, a back-up cuttingelement 12′ also may be secured within a cutting element pocket using abonding material 60.

Additional embodiments of methods of the present invention may be usedto repair a drill bit or another earth-boring tool. For example, afterthe drill bit 10 has been used to drill a wellbore, one or more of thecutting elements 12 may be removed from the cutting element pockets 16.A temporary displacement member 66 then may be secured within thecutting element pockets 16. A depth-of-cut control feature 50 then maybe formed or otherwise provided over the temporary displacement member66 and the surrounding surface 19 of the blade 18, as previouslydescribed herein. For example, the depth-of-cut control feature 50 maybe formed by depositing hardfacing material over an area of the surface19 of the blade 18 of the bit body 14 adjacent the cutting elementpocket 16, as well as over a surface of the temporary displacementmember 66. The hardfacing material may be built up over the temporarydisplacement member 66 to repair the cutting element pocket 16 and formthe depth-of-cut control feature 50 from the hardfacing material.Furthermore, the hardfacing material may be built up over the temporarydisplacement member 66 and the surrounding surface 19 of the blade 18sufficiently until the hardfacing material projects from the surface ofthe blade 18 by a predetermined distance D₁ (FIG. 3) when repairing thedrill bit 10. Furthermore, as previously discussed with reference toFIG. 3, the hardfacing material may be built up to provide apredetermined minimum surface area of the hardfacing material at thepredetermined distance D₁ above the surface of the blade 18 of the bitbody 14 when repairing the drill bit 10.

Although embodiments of the present invention have been described withreference to a fixed-cutter earth-boring rotary drill bit 10, it isunderstood that embodiments of methods of the present invention may beused to form other earth-boring tools including, for example, othertypes of drill bits (e.g., rotary roller cone bits, hybrid bits,percussion bits, coring bits, bi-center bits, eccentric bits, etc.),reamers, mills, and any other earth-boring tools that might include acutting element secured within a cutting element pocket and employ oneor more depth-of-cut control features.

While the present invention has been described herein with respect tocertain embodiments, those of ordinary skill in the art will recognizeand appreciate that it is not so limited. Rather, many additions,deletions and modifications to the embodiments described herein may bemade without departing from the scope of the invention as hereinafterclaimed, and legal equivalents thereof. In addition, features from oneembodiment may be combined with features of another embodiment whilestill being encompassed within the scope of the invention ascontemplated by the inventor.

What is claimed is:
 1. A method of forming an earth-boring tool, comprising: partially forming a cutting element pocket in a surface of a body of an earth-boring tool; inserting a temporary displacement member into the partially formed cutting element pocket; providing a particle-matrix composite material over an area of the surface of the body of the earth-boring tool adjacent the partially formed cutting element pocket and over a portion of a surface of the temporary displacement member to complete formation of the cutting element pocket and form a depth-of-cut control feature using the particle-matrix composite material; and removing the temporary displacement member from the completely formed cutting element pocket and securing a cutting element within the completely formed cutting element pocket.
 2. The method of claim 1, wherein providing the particle-matrix composite material over the area of the surface of the body of the earth-boring tool adjacent the partially formed cutting element pocket and over the portion of the surface of the temporary displacement member comprises depositing a hardfacing material over the area of the surface of the body of the earth-boring tool adjacent the partially formed cutting element pocket and over the portion of the surface of the temporary displacement member.
 3. The method of claim 2, wherein completing formation of the cutting element pocket and forming the depth-of-cut control feature using the particle-matrix composite material comprises building up the hardfacing material over the temporary displacement member to complete formation of the cutting element pocket and form the depth-of-cut control feature using the hardfacing material.
 4. The method of claim 3, wherein building up the hardfacing material over the temporary displacement member comprises building up the hardfacing material to a predetermined height above the surface of the body of the earth-boring tool adjacent the cutting element pocket.
 5. The method of claim 4, further comprising forming the depth-of-cut control feature to comprise a predetermined minimum surface area at the predetermined height above the surface of the body of the earth-boring tool adjacent the cutting element pocket.
 6. The method of claim 3, further comprising selecting the hardfacing material to comprise hard particles and a metal alloy matrix material.
 7. The method of claim 6, further comprising selecting the metal alloy matrix material to comprise at least one of an iron-based metal alloy, a cobalt-based metal alloy, and a nickel-based metal alloy.
 8. The method of claim 1, wherein inserting a temporary displacement member into the partially formed cutting element pocket further comprises selecting the temporary displacement member to comprise at least one of aluminum oxide and silicon oxide.
 9. The method of claim 8, wherein selecting the temporary displacement member to comprise at least one of aluminum oxide and silicon oxide comprises selecting the temporary displacement member to comprise about 95% by weight aluminum oxide and about 5% by weight silicon oxide.
 10. The method of claim 1, wherein the earth-boring tool comprises a rotary drill bit, and further comprising forming the body to comprise a bit body.
 11. The method of claim 1, further comprising providing another particle-matrix composite material having a different material composition over another area of the surface of the body of the earth-boring tool adjacent another partially formed cutting element pocket to complete formation of another cutting element pocket and form another depth-of-cut control feature using the another particle-matrix composite material. 